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https://issues.apache.org/jira/browse/NETBEANS-406?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
ASF GitHub Bot updated NETBEANS-406:
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Labels: pull-request-available (was: )
> addPropertyChangeListener w/o matching removePropertyChangeListener
> -------------------------------------------------------------------
>
> Key: NETBEANS-406
> URL: https://issues.apache.org/jira/browse/NETBEANS-406
> Project: NetBeans
> Issue Type: Bug
> Components: editor - CSL (API & infrastructure), editor -
> Painting & Printing
> Affects Versions: 8.2, 9.0
> Environment: NetBeans 9.0 beta
> (incubator-netbeans-release-205-on-20180202) on OpenJDK 64-Bit Server VM
> 9.0.4.1+11, Mac OS 10.9.5
> Reporter: Eirik Bakke
> Priority: Minor
> Labels: pull-request-available
>
> The following warning appears in the IDE log every now and then in 8.2 and
> 9.0 beta:
>
> {code:java}
> WARNING [org.openide.util.WeakListenerImpl]: Can't remove
> java.beans.PropertyChangeListener using method
> org.netbeans.modules.editor.NbEditorDocument.removePropertyChangeListener
> from org.netbeans.modules.editor.NbEditorDocument@299b063c,
> mimeType='text/x-editor-search', kitClass=null, length=9, version=15,
> file=null{code}
>
> The warning above can be reproduced by opening a Java editor, closing all
> editors, and then invoking a GC with by double-clicking the memory meter in
> the "Performance" toolbar item.
> This bug was previously discussed in Bugzilla at
> [https://netbeans.org/bugzilla/show_bug.cgi?id=196323] . Not sure what
> priority to put for this bug; it's a memory leak, but I'm not sure how big of
> an impact it has.
> *Analysis*
> Storing a stacktrace in WeakListenerImpl.ListenerReference on creation and
> then printing it on the failed removal shows the place where the problematic
> listener is added:
> {code:java}
> java.lang.Exception
> at
> org.openide.util.WeakListenerImpl$ListenerReference.<init>(WeakListenerImpl.java:554)
> at org.openide.util.WeakListenerImpl.<init>(WeakListenerImpl.java:109)
> at org.openide.util.WeakListenerImpl.<init>(WeakListenerImpl.java:99)
> at
> org.openide.util.WeakListenerImpl$PropertyChange.<init>(WeakListenerImpl.java:187)
> at org.openide.util.WeakListeners.propertyChange(WeakListeners.java:282)
> at
> org.netbeans.modules.editor.lib2.view.DocumentViewOp.checkSettingsInfo(DocumentViewOp.java:937)
> at
> org.netbeans.modules.editor.lib2.view.DocumentViewOp.checkViewsInited(DocumentViewOp.java:622)
> at
> org.netbeans.modules.editor.lib2.view.DocumentView.getPreferredSpan(DocumentView.java:251)
> at
> javax.swing.plaf.basic.BasicTextUI$RootView.getPreferredSpan(BasicTextUI.java:1353)
> at javax.swing.plaf.basic.BasicTextUI.getPreferredSize(BasicTextUI.java:919)
> at javax.swing.JComponent.getPreferredSize(JComponent.java:1662)
> at javax.swing.JEditorPane.getPreferredSize(JEditorPane.java:1333)
> at
> org.netbeans.modules.editor.NbEditorUI$LayeredEditorPane.getPreferredSize(NbEditorUI.java:475){code}
> The problem is on this line of DocumentViewOp:
> {code:java}
> o.n.modules.editor.lib2.view.DocumentUtilities.addPropertyChangeListener(doc,
> WeakListeners.propertyChange(this, doc));{code}
> The DocumentUtilities.addPropertyChangeListener is a special API for allowing
> property change listeners to be attached to BaseDocument instances (see
> Bugzilla [https://netbeans.org/bugzilla/show_bug.cgi?id=181073] ). Since it
> doesn't actually add addPropertyChangeListener/removePropertyChangeListener
> methods to BaseDocument, it doesn't work with WeakListeners.
> As far as I can see, the only place that actually uses
> DocumentUtilities.addPropertyChangeListener is the single line i
> DocumentViewOp above.
> I would propose adding a removedPropertyChangeListener method to BaseDocument
> that delegates to DocumentUtilities.removePropertyChangeListener (or performs
> the equivalent logic itself). This way the WeakListener will find the method
> it expects when the listener is due to be removed, and the property change
> events will still have the Document instance as the event source instead of
> the delegate PropertyChangeSupport, as is probably desired.
> An alternative is to make WeakListeners aware of the special setup wrt.
> property change listeners on BaseDocument instances. But that seems like an
> abstraction violation.
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